Growing points of DNA in cultured mammalian cells.
A fraction of DNA, known to be replicating, was examined in the electron microscope. Characteristic branch points were identified as sites at which replication had been taking place. No localized strand separations, nor other structural alterations were discernible at these points.
D002499:Centrifugation, Density Gradient; D002999:Clone Cells; D004261:DNA Replication; D008854:Microscopy, Electron; D013936:Thymidine / Q000378:metabolism; D014316:Tritium
D014316:Tritium; D013936:Thymidine